Rambidae ( Latin Rajidae ) - a family of cartilaginous fish from the order of stingrays ( Rajiformes ). Currently, 17 genera are assigned to it [1] . The maximum length, as a rule, does not exceed 180 cm [2] . The most famous rhombic species is the sea fox ( Raja clavata ), which is widespread off the coast of Europe and northern Africa (from the Canary Islands to Norway) and is found in the Black Sea , the Mediterranean Sea (rarely in the Sea of Azov) and the western part of the Baltic Sea. The smooth ramp ( Raja batis ) is considered to be under serious threat of extinction and is on the IUCN Red List .
| Rhombus ramps |
Amblyraja badia |
| Scientific classification |
|---|
| No rank : | Bilateral symmetrical |
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| International scientific name |
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Rajidae Blainville , 1816 |
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Content
Rhombus ramps live in all oceans from the Arctic to the Antarctic . Most species live in temperate latitudes on the sea muddy or sandy bottom [2] . Distributed both on the coastal shelf and in deep waters. In shallow water in the tropics and near coral reefs, representatives of the rhombic family are less common. Some species enter brackish waters [3] .
In rhombic ramps, wide and flat pectoral fins form a square or rhomboid disk. The tail is very thin, without a sting, with 2 lateral folds. The mouth is straight or arched in the form of an arch, with numerous teeth. In some species, weak electrical organs are located on both sides of the tail. The dorsal fins are usually 2. The pectoral fins reach the snout or merge with it. Caudal fin rudimentary or absent. There are species with a sharp or blunt front of the head. The skin is tough with spikes and spines, which are sometimes lined up in a row [2] [3] .
Typically, rhombic females are larger than males, they have a wider disk. Young individuals differ from adults in body proportions, tooth structure and the presence of spikes [2] .
The color of these bottom fish may vary depending on the color of the soil. As a rule, they prefer a smooth sandy or shell bottom. In the afternoon they are usually inactive and lie at the bottom, sometimes burrowing into the ground, with the help of pectoral fins. Sometimes they rise into the water column, pursuing prey. swim, flapping pectoral fins, like wings, can develop a fairly high speed. Stingrays cannot capture prey floating in the water column directly, since their mouth is located on the underside of the disk. Therefore, they float on top of their victim, press it to the bottom and swallow it [2] . The diet consists mainly of bottom organisms [3] .
Reproduction
Egg capsule
Raja binoculata Fertilization is internal. Unlike all other stingrays, among which live birth is common, rhombic stingrays are ovipositing. Large eggs are enclosed in horny egg capsules , which have a quadrangular shape with horn-shaped processes and respiratory fissures. Using the processes, the capsule is attached to the bottom. The total number of capsules depends on the species and can reach 50 or more. The shape of the capsule can determine the species. The incubation period before hatching can last from four to fourteen months [2] . Fossil remains give reason to say that previously rhombic stingrays reproduced by live birth [3] .
Currently, 17 genera are assigned to families [1] :
- Amblyraja Malm, 1877
- Beringraja Ishihara, Treloar, Bor, Senou & Jeong, 2012
- Breviraja Bigelow & Schroeder , 1948 - Short Rays [4]
- Dactylobatus Bean & Weed, 1909 - Dactylobates
- Dentiraja Whitley, 1940
- Dipturus Rafinesque, 1810
- Fenestraja McEachran & Compagno, 1982
- Gurgesiella de Buen, 1959 - Stingrays-gurgesiella
- Hongeo Jeong & Nakabo, 2009
- Leucoraja Malm, 1877
- Malacoraja Stehmann, 1970 - Soft Rays
- Neoraja McEachran & Compagno, 1982
- Okamejei Ishiyama, 1958
- Raja Linnaeus, 1758 - Rhombic rays (genus)
- Rajella Stehmann, 1970
- Rostroraja Hulley, 1972
- Zearaja Whitley, 1939
- ↑ 1 2 Rajidae (English) in the World Register of Marine Species database. (Retrieved December 18, 2012)
- ↑ 1 2 3 4 5 6 Animal life. Volume 4. Lancelet. Cyclostomes. Cartilaginous fish. Bone fish / ed. T. S. Rassa , ch. ed. V. E. Sokolov . - 2nd ed. - M .: Enlightenment, 1983. - S. 46-47. - 300,000 copies.
- ↑ 1 2 3 4 Froese, Rainer, and Daniel Pauly, eds. Family Rajidae - Skates (Neopr.) . FishBase
- ↑ Reshetnikov Yu.S. , Kotlyar A.N. , Russ T.S. , Shatunovsky M.I. The Bilingual Dictionary of Animal Names. Fish. Latin, Russian, English, German, French. / edited by Acad. V. E. Sokolova . - M .: Rus. Yaz., 1989 .-- P. 41 .-- 12,500 copies. - ISBN 5-200-00237-0 .
